Treatment of molasses fermentation solutions



' .March 30, 1943. F. M. HILDEBRANDT TREATMENT OF MOLASSES ERMENTATION SOLUTIONS Filed Feb. .14, 1941 IN VEN TOR.

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Patented Mar. 30, 1943 TREATMENT OF MOLASSES FERMNTA- TION SOLUTIUNS Frank M'. Hildebrandt, Baltimore, Md., assignor to U. S. Industrial Alcohol Co., New York, N. Y., a corporation of WestVirginia Application February 14, 1941, Serial No. 378,884

(ci. 2oz-74) 4 Claims.

This invention is a process of treating cane molasses fermentation solutions whereby certain high-boiling organic substances heretofore difficult to recover from such solutions are recoverable in a facile manner, and whereby substances that would prevent or interfere with recoveries, or clog the system, are conditioned so that they do not interfere and themselves offer a vvaluable product.

The dissolved, or dissolved and suspended solids. of these solutions include various non-volatile organic compounds and bodies as well as those of inorganic nature, and it is these substances which cause diiculty in certain operations by reason of their tendency to agglomerate, to adhere to surfaces of apparatus and pipes, and to cause clogging and local overheating.

The invention is applicable to the treatmentI of molasses still-residue, namely the dealcoholized fermentation solution from yeast fermenta-` tion of amolasses mash. In the usual fermentation for ethyl alcohol these still residues contain a quantity of glycerine amounting to about 3% of the fermented sugar, but this glycerine has not been commercially recoverable, and in the aggregate enormousquantities of glycerine have gone to waste in the still residues. Commonly these still residues are disposed of by running them into rivers or other Waters.`

Not only does the ordinary molasses stillresidue' contain a small amount of glycerine: it is known'to be possible to increase this content readily to 14% of the sugar fermented or .even to higher percentages under special conditions. Again, however, it has not been economical or practical to recover the glycerine.

I have discovered that by feeding the molasses still residue to a body of a suitable liquid, maintained at a sufficiently high temperature, not merely will the glycerine and water be flashed olf together, but the solids, which remain in the hot bath, will be finely-divided, non-agglomerating, non-adherent. and when subsequently freed of bath liquid substantially non-hygroscopic. Consequently the operation can be conducted successfully, Whether for glycerine or of solids, or both. The solid product contains both the potash and much of the nitrogen of thev still-waste and is a valuable fertilizer material. v

The treatment is equallyapplicable to mo'- lasses solutions which have been fermented by. the action of micro-organisms to produce lactic acid. The problem created by the presence of the organic'molasses solids is4 the same as in the case of the'still-residues from ethanol or ethanolglycerol fermentations, and substantially the same order of heating will condition the solids of the lactic fermentation solutions in the inan-l ner and to the ends that have been described.

Lactic acid, which like glycerol has a. boiling point above the boilingpoint of water, is flashed off with the water, the solids are altered in composition and physical tendencies and separate as discrete particles in the bath, and from which they are readily removable.

The bath temperatures to be employed in the process of the invention are of the order of 190- 280 C., and preferably of the order of 230- 280" C. In order properly to condition the solids and flash olf the liquids the temperature should be kept above 190 c. and better sun above 2ho c. For best recoveries of glycerine or lactic acid, temperatureswell above 200 C. are required. In my experience I have found temperatures of about 250 C.-to be satisfactory as regards both the solids and the high-boiling organic constituent. l

If the feed to the process be the still-residue of an ethyl alcohol fermentation, it mayor may not be a primary object to' recover glycerine. For recovery especially of glycerine, or of lactic acid in the other applicationof the invention, the temperature of the bath should not be so high as to cause undue decomposition of the glycerine or lactic acid.

In order tov maintain the temperature of the .I

bath it is preferable to circulate the bath liquid to and from a capacious treating vessel, through an external heater. In this connection I have found a simple way of removing the solids from the treating vessel. which consists in taking off a side stream to a filter, said side stream preferably by-passing the heater.

The accompanying drawing is a diagrammatic illustration of apparatus for carrying out the invention. l

A treating vessel or still 2 contains a body of heat-transfer liquid 3 which is circulated by a pump 4 through pipes 5, 6, 'l from the treating vessel to a heating coil in a furnace 8, 'and back to the Vessel. v

The molasses still-residue, or slop, preferably concentrated to about 50% solids content, is inrccovery of r troduced into contact with the hot bath through a pipe 9. The feed is preferably injected into the bath at a substantial distance below the surface of the latter. It is not necessary to provide special means for spraying or atomizing the feed solution, since the explosive effect of sudden va`- porization breaks it up into small droplets, with the result that the solids separate in line particles.

The bath liquid should be one that is substantially heat-stable, substantially non-miscible with water, substantially a non-solvent rof the solids, substantially non-reactive with the constituents of the feed, and has a boiling point higher than the temperature at which the flash distillation is effected. l For the recovery of glycerine or lactic -totaloil circulated. /l y l Y nitrogen. 'I'his end-producthas eels it should be substantially lmmlselble with. the product in question. It should have a specific gravity such that the solids produced do not float on top of the bath but settle or remain in the bodyofthe liquid in orderv that their removal may be accomplished in the manner described. A

vmineral oil is preferred. i An oil that has been found satisfactory has the following character--` istics:

, a Degreescentigrade nitialbolng point at 'atmospheric pressure' 305 50% 337 End point n t 377 v-Gravity 0.874 at 30 In the case Aof still-residue, the vapors of glycerine and water are ashed oil on contactv ofjthe feed with the hot oil, and enter vthe condenser I0 at a temperature ,upwards of '180 C.and preferably upwards of 200 C,A -The condensate goes through the cooler Il .into the decanting vessel l2. The upper layer consisting of oil is put vback intothe treating `vessel 2 through pipe lI l, and the lower` layer, which contains the waterv of the feed together with the glycerine and certain impurities,

is drawn-from the decanter to the receiver il, tou

be subsequently concentrated and puried in any desired manner.

' The solids,'conditione d in thetreating vessel b er of ways. Much advantage, however, is realized by drawing oil' a small side stream of the liquid, carrying the solids in suspenslon,to a

filter l5, preferably of the continuous, rotary,

vacuum type.l This stream, whichl does not pass throughv the' furnace, may be taken oil!` from the pipe 6 at av point between the main circulating which the yclear liquidreturns to the still or treating vessel through a line I8,-.a receiver I! having a vacuum connection 20, and a pump 2l.

This 'method of withdrawing solids results in .a

build-up of solidsin lthe Abath liquid circulating through the still until an equilibrium isreached,

' at which the solids arefwithdrawn at the same rate as they are formed'. 5 The value .per minute of thesde stream need `benogreater than 5 7b of the vf-The solid product, when freed o f bath liquid in the iilter orotherwise, is a dark, substantially nonhygroscopic powder, containing-on the dry basis about 14%v to 15% potash and bout 2.25%

actuel tests to be a valuable fertulzerlngr'eaient. .When mixed with other materials, mainly phos- `phates, it becomes a complete fertilizer.

f '.In thev treatment of molasses lactic-acid fer-- mentation solutions, the lactic solution is fed 'through the pipev 9, the vapors of lactic acid and water are flashed oil' and go to the condenser I8, the residual molasses solids are conditioned in the bath,and when removed and freed of the heat'- transfer liquid constitute a solid product similar to that from the ethyl alcohol still-residue or slop.

-.It is desirable to supply a small current of superheated'steam to sweep the lactic acid vapors out i l. of thevessel 2.

Y This application is a Vcontinuation in part of my application Serial No. 235,696, filed Octnber l 2 as heretofore described, may be removed from i Y the vessel and freed ofthe bath liquid in a numi pump 4 and the furnace. It passes through a., valved line I6 and a cooler I1 to the filter, from containing a vbody of heat transfer liquid that has a boiling. point highertha'n temperature'used ln thepreeeseend'tnatis nonvr'eaetive with seid solution, flashing oilcertaingvolatile substancesof the soiution and chanting thefiihi'salflop'erties of said'. solids into' nonfagfglpmerating, .'.non-adherent. finely-divided by jmixins said solidswltn tnefnquidilntneyessei anilmeinteining .the temperatureof thefllquicl-above 190 C.,

removing thebhyscallyichangedsclids'from said'- vessel withs pcrtlonfof the" hea# transfer liquid, andvsubseqentlv separati@ .from the heat transterliqidto securel ga, product that is fertilizer material.v i o Theprocess of` ,fp ting Lmolassesfermentation solution `as described'in claim *1 in whichvthe neet trenefer'nqulsisorgsol at a temperature-between 199 "3. The process of heat treatin;

'molasses fel'- mentationjsolution containing a'fsubstantialprof Y portion of solidsubstanes lto agglom.. erste and toadhe're'to; apparatus and pipes of treatingequipmentfcsusing clogging and local overheating, which; yprocess; comprises fthe' following stepszff the finolasses Vfetmentation solution into asvessel containing .a body of organic heattransfer liquidvnon-reactive withV the fermentation "solution and having a, boiling point highexgtlian temperature of the process, f said'heat transferjliquid beingl maintained at a' temperature suiliciently high toilash of! the volatiles and to put thelsolids into-a non-agglomerating and non-adhesive condition, nashin'g-ofithe volatile substances'fin Vthe said solution includingy the water andlother )volatilesboilinglabove vtli boiling pointeiweter end recovering the naslledoff materials byfcondensation, removing the physlcsnyehangeillselios 'fromthe 'treating vessel with y a portionlof the lieattran'sferliquid, and subse- .quently separating the solids from the heat transfer liquid to secures; product kthat is a fertilizer material. f' n. v

4.' The process oftreatlng the still-residue from an ethyl alcoholfermentation of molasses'whlch residue containswater,v glycerine, ,andA a substantial proportion solid substances that tendl to agglomeratev and ffto a ladhere lto' the surfaces of treating apparatus, process comprising introducing the still-residue'into a vessel containing a body of heat transfer liquidl that is non-reactive with the still-residue, flashing oil the water' and glycerine of the solution and condensing them in another vessel that is in communication with the vessel containingthe heat transfer liquid, changing the physical properties of the solids by. mixing said solids with the heat transfer liquid and maintaining the temperature of the liquid' above 190 C., removing the physically-changed solids from said vessel with a portion of the heat transfer liquid, and subsequently separating the solids from the heat transfer liquid to secure a product thaivis fertilizer material,

FRANK M. HIIDEBRANDT. 

